Warm Up Lesson Presentation: Notes page Lesson Quizzes

Warm Up 1. What is the area of a rectangle with length 10 cm and width 4 cm? 2. What is the area of a parallelogram with base 18 ft and height 12 ft? 3. What is the area of a triangle with base 16 cm and height 8 cm? 40 cm2 216 ft2 64 cm2

Example 1: Finding Areas of Composite Figures Find the area of the polygon. 1.7 cm 4.9 cm 1.3 cm 2.1 cm Think: Break the polygon apart into rectangles. Find the area of each rectangle.

Example 1 Continued 1.7 cm 4.9 cm 1.3 cm 2.1 cm A = lw A = lw Write the formula for the area of a rectangle. A = 4.9 • 1.7 A = 2.1 • 1.3 A = 8.33 A = 2.73 8.33 + 2.73 = 11.06 Add to find the total area. The area of the polygon is 11.06 cm2.

Example 2: Finding Areas of Composite Figures Find the area of the polygon. Think: Break the figure apart into a rectangle and a triangle. Find the area of each polygon.

Example 2 Continued A = bh 1 2 __ A = lw A = • 28 • 12 1 2 __ A = 28 • 24 A = 168 A = 672 Add to find the total area of the polygon. 672 + 168 = 840 The area of the polygon is 840 ft2.

Example 3 Find the area of the polygon. 1.9 cm 1.9 cm 5.5 cm 1.5 cm 2 cm 5.5 cm 1.5 cm 2 cm 3.4 cm Think: Break the polygon apart into rectangles. Find the area of each rectangle.

Example 3 Continued 1.9 cm 5.5 cm 1.5 cm 2 cm A = lw A = lw Write the formula for the area of a rectangle. A = 5.5 • 1.9 A = 2 • 1.5 A = 10.45 A = 3 10.45 + 3 = 13.45 Add to find the total area. The area of the polygon is 13.45 cm2.

Example 4 Find the area of the polygon. 20 ft 22 ft 16 ft 36 ft 20 ft 22 ft Think: Break the figure apart into a rectangle and a triangle. Find the area of each polygon.

Example 4 Continued 16 ft 20 ft 22 ft 22 ft A = bh 1 2 __ A = lw A = • 22 • 16 1 2 __ A = 22 • 20 A = 176 A = 440 Add to find the total area of the polygon. 440 + 176 = 616 The area of the polygon is 616 ft2.

Additional Example : Art Application Patrick made a design. Use the coordinate grid to find its area. Think: Divide the design into rectangles. Find the area of each rectangle. Rectangle 1 l = 5, w = 5; A = 5 • 5 = 25 25 20 Rectangle 2 15 l = 10, w = 5; A = 10 • 5 = 50 10 Rectangle 3 5 l = 15, w = 5; A = 15 • 5 = 75 5 10 15 20 25 Rectangle 4 l = 20, w = 5; A = 20 • 5 = 100

Additional Example Continued Add the areas of the four rectangles to find the total area of the design. 25 + 50 + 75 + 100 = 250 square units. The area of the design is 250 square units.

You can also count the squares and multiply by the area of one square You can also count the squares and multiply by the area of one square. 1 square = 25 square units. 10 • 25 = 250 square units. Helpful Hint

Lawanda made a design. Use the coordinate grid to find its area. Check It Out: Example 2 Lawanda made a design. Use the coordinate grid to find its area. Think: Divide the design into rectangles. Find the area of each rectangle. Rectangle 1 25 l = 5, w = 10; A = 5 • 10 = 50 20 1 15 2 Rectangle 2 10 3 l = 5, w = 15; A = 5 • 15 = 75 5 Rectangle 3 5 10 15 20 25 l = 5, w = 10; A = 5 • 10 = 50

Check It Out: Example 2 Continued Add the areas of the three rectangles to find the total area of the design. 50 + 75 + 50 = 175 square units. The area of the design is 175 square units.

Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems

Lesson Quiz 1. Find the area of the figure shown. 220 units2 2. Phillip designed a countertop. Use the coordinate grid to find its area. 30 units2

Lesson Quiz for Student Response Systems 1. Find the area of the figure. A. 27 units2 B. 54 units2 C. 93 units2 D. 98 units2

Lesson Quiz for Student Response Systems 2. Paul arranged tiles to form a model. Use the coordinate grid to identify its area. A. 25 square units B. 18 square units C. 21 square units D. 16 square units